全文获取类型
收费全文 | 495878篇 |
免费 | 51804篇 |
国内免费 | 172篇 |
专业分类
547854篇 |
出版年
2018年 | 5884篇 |
2017年 | 5446篇 |
2016年 | 7645篇 |
2015年 | 9991篇 |
2014年 | 11335篇 |
2013年 | 15471篇 |
2012年 | 17716篇 |
2011年 | 17549篇 |
2010年 | 11895篇 |
2009年 | 10519篇 |
2008年 | 15549篇 |
2007年 | 15842篇 |
2006年 | 15091篇 |
2005年 | 14009篇 |
2004年 | 14028篇 |
2003年 | 13035篇 |
2002年 | 12649篇 |
2001年 | 18966篇 |
2000年 | 18876篇 |
1999年 | 15036篇 |
1998年 | 5543篇 |
1997年 | 5665篇 |
1996年 | 5338篇 |
1995年 | 5014篇 |
1994年 | 4845篇 |
1993年 | 4842篇 |
1992年 | 12315篇 |
1991年 | 12207篇 |
1990年 | 11940篇 |
1989年 | 11623篇 |
1988年 | 11066篇 |
1987年 | 10664篇 |
1986年 | 9920篇 |
1985年 | 9856篇 |
1984年 | 8271篇 |
1983年 | 7170篇 |
1982年 | 5560篇 |
1981年 | 4982篇 |
1979年 | 7967篇 |
1978年 | 6284篇 |
1977年 | 5824篇 |
1976年 | 5577篇 |
1975年 | 6091篇 |
1974年 | 6836篇 |
1973年 | 6675篇 |
1972年 | 6234篇 |
1971年 | 5640篇 |
1970年 | 5089篇 |
1969年 | 5077篇 |
1968年 | 4903篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
232.
233.
Elevated serum gamma-glutamyl transferase (GGT) levels were found in 29% of 155 chronic alcoholics undergoing detoxification treatment. Alkaline phosphatase (AP) was increased in 16%, alanine aminotransferase--SGPT (ALT) in 12% of the patients, while 23% had elevations of either AP or ALT or both. Of the foregoing parameters, GGT was the best single indicator of liver involvement. In course of the follow-ups GGT/ALT correlation improved, but GGT/AP correlation deteriorated. In 9 patients, abstinence during follow-up was associated with progressive decrease in previously elevated serum GGT. Because of its unique sensitivity, GGT may be useful as a screening and/or monitoring aid in alcoholism. 相似文献
234.
E. B. Burova I. S. Smirnova A. N. Shatrova I. V. Gonchar N. N. Nikolskii 《Cell and Tissue Biology》2011,5(1):9-14
Interferon gamma (IFNγ) is known to inhibit the proliferation of some transformed cell lines. Recently, we demonstrated the
transactivation of the epidermal growth factor receptor (EGFR) in response to IFNγ (Burova et al., 2007) and provided direct
evidence for the dependence of IFNγ-induced EGFR transactivation on the EGFR expression level in epithelial cells (Gonchar
et al., 2008). This study examines an antiproliferative effect of IFNγ on human epithelial cell lines—A431 and HeLa that express
high levels of EGFR, as well as HEK293 that expresses low levels of EGFR. To characterize the IFNγ-induced changes in these
cells, we studied cell growth, the cell cycle, and induction of apoptosis. The response to IFNγ differed in the compared cell
lines; cell growth was inhibited in both A431 and HeLa cells, but not in HEK293 cells, as was shown by the cell count and
MTT. The cell-cycle phases analyzed by flow cytometry were disturbed in A431 and HeLa cells in response to IFNγ. On the contrary,
in HEK293 cells, the IFNγ treatment did not alter distribution by cell cycle phases. Our results indicate that IFNγ produces
an antiproliferative effect that depends on the increased expression of EGFR in A431 and HeLa cells. Furthermore, it was demonstrated
that IFNγ induced the caspase 3 activation in A431 cells, which suggests the involvement of active caspase 3 in the IFNγ-induced
apoptosis. 相似文献
235.
236.
237.
238.
239.
Effects on Plant Growth Produced by Azotobacter paspali Related to Synthesis of Plant Growth Regulating Substances 总被引:2,自引:2,他引:0
S ummary . Treating seedling roots of several plant species with cultures of Azotobacter paspali changed plant growth and development and significantly increased weight of leaves and roots; effects were probably caused by plant growth regulators. Culture supernatant fluids contained indolyl-3-acetic acid, at least 3 gibberellins and 2 cytokinins. The added inoculum of A. paspali survived in plant rhizospheres for only a few weeks and no nitrogen was fixed in the root zone of young Paspalum notatum , the grass with which A. paspali is associated. 相似文献
240.
S. T. Zakhidov T. L. Marshak E. A. Malolina A. Yu. Kulibin I.A. Zelenina S. M. Pavluchenkova V. M. Rudoi O. V. Dement’eva S. G. Skuridin Yu. M. Evdokimov 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2010,4(3):293-296
The effect of gold nanoparticles on mouse epididymal sperm has been studied using the model system of nuclear chromatin decondensation
in vitro. It is shown that the treatment of gametes, preliminary membrane-freed by sodium dodecyl sulfate, in the mediums
containing gold nanoparticles (with diameter ∼2.5 nm) in concentrations 1.0 × 1015 or 0.5 × 1015 particles/ml and following incubation in dithiothreitol solution (DTT) resulted in failure of chromatin decondensation process
and nucleus structure. We conclude that gold nanoparticles possess spermatotoxicity. The mechanism of cytotoxic effect of
gold nanoparticles may be related with their interaction with molecules of double-helix DNA. The model system studied in this
research is applicable for further investigations of cytotoxic effects of nanoparticles of different origin and made of different
metals. 相似文献